The automobile steering knuckle is a very important part in an automobile, and its machining process is very complicated. Different holes in the steering knuckle are assembled with different parts, so the position of each hole is very important. The positions of mounting holes for sensors and threaded holes for fixing the sensors on steering knuckles of different structural types are very important detected parameters, which directly affects whether the sensors can be assembled normally. At the same time, the requirement for the depths of the threaded holes is also very high. Thus, a detection tool that can detect the position of a threaded hole relative to an unthreaded hole and the depth of the threaded hole is needed.